function createXMLHttpRequest() { 
  var xmlHttpReq;
  if (window.XMLHttpRequest) {
    xmlHttpReq = new XMLHttpRequest();
    xmlHttpReq.overrideMimeType('text/xml');
  } else if (window.ActiveXObject) {
    xmlHttpReq = new ActiveXObject("Microsoft.XMLHTTP");
  } 
  return xmlHttpReq;
}